Inspired by the rebellious Spaniards' success against Napoleon, Austria launched a campaign to liberate neighboring countries from Napoleon's rule. Hoping to inspire large-scale revolution throughout the Confederacy of the Rhine, Austrian troops invade Bavaria on April 8, 1809, proclaiming a War of German Liberation. But the people of Bavaria, who had profited from Napoleon's earlier defeat of Austria, rallied once again around Napoleon as he assembled his troops for battle.

"Austria wants to get slapped; she shall have it," Napoleon boasted. "If the Emperor Francis attempts any hostile move, he will soon have ceased to reign."